Electrochemical processing of inner surfaces of large vessels

ABSTRACT

A portable electrode assembly is disclosed for passage through restricted openings and convenient set-up within relatively large vessels for the purpose of electrochemically processing or treating the inner surface of the vessel without removing the vessel from its associated permanent support structure. In preferred embodiments, high density electrolyte solutions are used with electrode assemblies which include means for displacing substantial quantities of the electrolyte while providing support for the electrode elements.

United States Patent [191 Jumer [451 Dec. 31, 1974 ELECTROCHEMICALPROCESSING OF INNER SURFACES OF LARGE VESSELS [76] Inventor: John F.Jumer, 16 West Timber Trails Dr., Elmhurst, 111. 60126 [22] Filed: July23, 1973 [21] Appl. No.: 381,693

Related U.S. Application Data [62] Division of Ser. No. 173,581, Aug.20, 1971, Pat. No.

[52] U.S. Cl; 204/26, 204/129.6, 204/212 [51] Int. Cl. C23b 5/56, C23b5/68 [58] Field of Search 204/26, 129.6

[56] References Cited UNITED STATES PATENTS 108,510 10/1870 Parmelee204/26 1,772,074 8/ 1930 Engelhardt et a1. 204/26 1,794,487 3/1931Schwartz 204/26 3,616,341 10/1971 Jumer 204/l29.6

FOREIGN PATENTS OR APPLICATIONS 455,810 10/1936 Great Britain 204/26915,006 l/1963 Great Britain.... 193,875 8/1967 U.S.S.R 204/26 PrimaryExaminer-T. M. Tufariello Attorney, Agent, or Firm-Lockwood, Dewey,Zickert & Alex [57] ABSTRACT A portable electrode assembly is disclosedfor passage through restricted openings and convenient set-up withinrelatively large vessels for the purpose of electrochemically processingor treating the inner surface of the vessel without removing the vesselfrom its associated permanent support structure. In preferred embodiments, high density electrolyte solutions are used with electrodeassemblies which include means for displacing substantial quantities ofthe electrolyte while providing support forthe electrode elements.

3 Claims, 9 Drawing Figures ELECTROCHEMICAL PROCESSING OF INNER SURFACESOF LARGE VESSELS This is a division of application Ser. No. 173,581,filed Aug. 20, 1971, now US. Pat. No. 3,772,163.

This invention relates to innovations and improvements in theelectrochemical treatment of interior surfaces of vessels which arepermanently mounted and fitted with relatively narrow manways. Theinvention can be utilized for conveniently and economicallyelectroplating, electropolishing, anodizing, electrocleaning or forother electroprocessing or electrotreating operations on the innersurfaces of vessels.

Large vessels are widely used in industry as reactors or pressurevessels and usually they are installed permanently secured on associatedsupport structures in a vertical or upright position. Many such vesselsare enclosed within buildings, and the operations involved in removingsuch a vessel for processing its inner surface are usually prohibitivelyexpensive. Moreover, many such vessels are installed with mechanicalsupport structure which is only adequate to safely accomodate fluidswhich have relatively low specific gravities, e.g., 1.0 or less. Hence,it is often unsafe to fill such equipment with a high densityelectrolyte, e.g., one having a specific gravity of approximately 1.7,such as are commonly used in connection with electropolishing, forexample. Furthermore, most tanks, reactors, and pressure vessels of theclass described are not provided with large removable lids or ends, andthe entrance openings, typically a manway, tend to be quite small,relatively speaking. For example, a small manway with hinged and boltedhatch or cover may serve a vessel of 5,000 gallon capacity.

Moreover, because of the extremely large capacity of many uprightreactors, pressure vessels, and other vertical vessels widely used inindustry, it would be most undesirable to fill such vessels withelectrlyte solution to capacity in order to immerse the electrodetherein. After use in electrochemical processing, generally, electrolytesolutions are recovered for salvage of metal values, and in any event,are generally not discharged into sewers because of potentially adverseimpact on municipal sewage treatment plants, streams, and the like. Thelarge volume of electrolyte to be recovered and reclaimed, if such largevessels were filled to capacity, would make such an operationundesirable.

It is an object of the present invention to provide a method and anelectrode apparatus by which vessels of the class described can beprocessed in place by electrochemical processing. It is another objectof the present invention to provide an electrode assembly or apparatusin which electrodes can be positioned singly or in multiples fixed ormovable, and with the active areas of the electrodes juxtaposed andsubstantially uniformly spaced from the interior surface of the vesselbeing processed for a period of time necessary to adequately process theinside surface. Moreover it is an object of the present invention toprovide such an electrode system for electrochemical processing of theinside of a relatively large vessel using high density electrolytesolution even though the vessel be designed for use in connection withrelatively low density fluid.

It is another object of the present invention to provide an apparatusand a method for electrochemical processing of inner surfaces of largevessels which achieve effective electrochemical processing of theinterior surface of said vessel without requiring that the vessel befilled to capacity with high density electrolyte solution.

Many upright tanks or pressure vessels have a domed bottom and a domedtop which can be referred to as heads, with central openings or ports inthe bottom for emptying, etc. and with central ports and/or nozzles inthe top. It is an object of the present invention to utilize central topand bottom ports for the introduction and operation of an electrodesystem which can be introduced through a manway for the purpose ofelectrochemically processing the inside surface of the vessel. It is afurther object of the present invention to provide an electrode systemwhich can be adapted for use to electrochemically treat only a portionof the total inside area of the vessel at any one time, whereby powerequipment and conductor size is reduced to a conveniently practicallevel, and also the problem of gas accumulation in the underside of thetop head is reduced or eliminated. It is a further object of the presentinvention to provide an electrode system which can be shaped to conformto standard top and bottom head configurations whereby the top andbottom head of the vessels can be electrochemically treatedsimultaneously with the substantially cylindrical side walls of thevessel.

These and other objects are achieved in accordance with the presentinvention, which is described in connection with preferred embodiments,as well as in general terms in the following description with the aid ofthe accompanying drawings in which:

FIG. 1 is a vertical sectional view with certain parts shown inelevation, of a preferred embodiment of the invention as applied to alarge vertical permanently mounted vessel;

FIG. 2 is a top plan view of the structure illustrated in FIG. 1;

FIG. 3 is a sectional view taken on line 33 of FIG.

FIG. 4 is a reduced scale cross-sectional view taken approximately alongthe line 44 of FIG. 1;

FIG. 5 is an enlarged fragmentary detail sectional view taken on line 55of FIG. 3 showing the upper electrical connection with one electrodeelement;

FIG. 6 is a fragmentary partially cross-sectional elevational view ofanother embodiment of this invention in a large vertical permanentlymounted vessel;

FIG. 7 is a sectional view taken on line 7-7 of FIG.

FIG. 8 is a partially sectional view of an alternative embodiment ofthis invention; and

FIG. 9 is a partially sectional view of another alternative embodimentof the present invention.

Referring to FIG. 1, a large vessel is generally indicated at 10. Forthe purpose of simplifying and clarifying the illustration of theinvention, FIG. 1 does not show all of the conventional support elements11 for supporting vessel 10. It is to be understood that vessel 10 isintended to illustrate any one of many well known reactor or pressurevessels. These vessels commonly are enclosed within a building, and mayextend through one, two or more stories of the building. Typically thevessels such as 10 are provided with at least a manway in the top 12 anda bottom drain opening 14. The manway 12 and drain opening 14 typicallyhave flanges l6,

18, respectively. It is to be understood that in a specific installationvessel 10 may have one or more conventional inlet or outlet connectionswhich communicate with the interior 20 either through domed top 22,domed bottom 24 or the side wall 26.

Typically manway 12 is accessible from a catwalk generally indicated at30 which is supported on vessel or on other conventional structuralelements.

A preferred electrotreating apparatus for vessel 10 in accordance withthis invention is indicated generally at 32. The electrode apparatusincludes a pair of copper mesh electrodes 34, 36 supported on a largeinflatable plastic liquid displacing bag 40 having a capped stem 42. Bag40 is toroidal in horizontal section and in exterior shape conformsgenerally to the interior of the vessel 10. The bag 40 has a centrallylocated cylindrical passageway 46, cylindrical inner wall 48, a numberof reinforcing dividers 50 connecting inner wall 48 and outer wall 52.Band 54 formed of stiffly resilient dielectric material passes aroundbag 40 near the lower end thereof and serves to reinforce the bag 40inthe-regions of insulated spacing rollers 56 and also provide support forthe rollers. It will be appreciated that three or more of rollers 56should be used around the circumference of band 54 to maintain properclearance between side walls 26 and electrodes 34, 36.

In the embodiment illustrated in FIGS. 1 through 5, electrodes 34, 36include elongated curved wall portions 60, 61 respectively, whichconform to the inside laterial face 26, and two sector shaped portions62, 63 conforming to bottom 24, and top 22, respectively. Referring toFIGS. 3 and 5, the respective radially innermost or terminal ends ofelectrode 34, 36 are clamped between respective clamping bars 64, 66 bynuts and bolts generally indicated at 68. Clamping bars 64, 66 areelectrically connected to each other by means of electrically conductivecross bars 69. Electric lead 70 is bolted to clamping bar 64 andprovides uniform distribution of current to both electrodes 34, 36.Cross bars 69 are clamped between tightenable sections of a two-partcollar 71, one part of which is fixed to rod 72. Clamping bars 64, 66,and cross bars 69, and collar 71 can be considered an electrode supportassembly 73, and an identical assembly 73 fastens the other ends of theelectrodes 34, 36. Collar 71 is formed of dielectric material so as toinsulate rod 72 from cross bars 69.

In assembling the apparatus 32 shown in FIG. 1, electrodes 34, 36 arepassed through manway l2, and bag 40 is passed through manway 12 incollapsed condition. One or more bands 54 are passed through manway 12in open condition and ends are joined to provide resilient annularstructures 54. Rod 72 is then passed through manway 12, and seated insocket 74. Collar 71 can be fastened to rod 72 before its entry intovessel 10, and clamping bars 64, 66 and frame assemblies 73, 73,generally, can be attached, as described hereinbefore, while insidevessel 10. Electrodes 34, 36, are fasted to bands 54, and to clampingbars 64, 66. Bag 40 is fastened to bands 54, while unfilled, and theassembler leaves the vessel before spider 84 is secured.

In order to provide for accurate location and operation of the apparatus10 of this invention, rod 72 extends through passageway 46 and issecured at its bottom end in thrust bearing 74 of known type capable ofabsorbing downward thrust resulting from the weight of the electrodes34, and 36, and liquid-displacing container or bag 40. Thrust bearingassembly 74 is secured to end plate 76 which, in turn, is bolted to T 78having valved side outlet 80. The upper portion of rod 72 is supportedin suitable thrust bearing assembly 82 which is maintained centered inmanway 12 supported in the center of a spider 84. The thrust bearing 82should be capable of absorbing the upward thrust due to buoyancy of theliquid-displacing container or bag 40. Handle wheel 86, and top andbottom frame members 73, 73 are fixed with respect to rod 72. Hencerotation of handle 86 causes rotation of rod 72 and, with it, frameelements 73, 73' and the rest of the electrode assembly 32. It will beappreciated from a consideration of FIG. 3 that the electrodes 34, 36cover a relatively small portion of the surface area of the inflated bag40. For example in the embodiment illustrated in FIGS. 1 through 5electrodes 34, 36 are each approximately 50 inches wide and togethercover approximately 28percent of the total exterior of displacer 40.

Thus in the embodiment illustrated in FIGS. 1 through 5, electrodes 34,36 can be considered to be axially extending elongated strips and theentire surface of the vessel 10 can be electrochemically treated byrotated electrode assembly 32 around its elongated vertical axis.

In operation of the invention a conventional electrolyte is pumped intovessel 10, and a liquid-displacer such as water is charged to bag 40until vessel 10 and bag 40 are filled. Thus only a relatively smallamount of electrolyte is required.

During operation of the apparatus of the present invention, vessel 10 iselectrically grounded and an electrical potential is applied atelectrical lead 72. Whether the lead 72 is made positive or negativedepends on whether electroplating, electropolishing, etc. is to beperformed. Handle 86 is turned as desired to rotate as sembly 32 touniformly process the entire inner surface of the tank.

An alternative embodiment is shown in FIGS. 6 and 7 in which anelectrode extends 360 horizontally but extends along a relatively shortportion of the vertical length of the side wall of the vessel theinterior of which is to be electroprocessed. In this alternativeembodiment portions of the vessel and associated structures correspondto those shown in FIGS. 1-5, and are identified in FIGS. 6 and 7 byprimed numbers.

The alternative electrode assembly is generally indicated by the numeral90 in FIGS. 6 and 7 and includes electrode 92. A substantially toroidalbag 40 is positioned within closely adjacent screen electrode 92 and, inthe illustrated embodiment, electrode 92 has relatively short laterallyfacing portions 94 and end walls 96. Laterally facing portions 94 aremaintained spaced apart from inside lateral face 26' of vessel 10 byinsulated rollers 56' whose axles run horizontally, rather thanvertically. Bag 40' is equipped with a stem 42' for filling and emptyingand'is toroidally shaped to provide vertically extending innerpassageway 46'. A rope or cable passes around drum 102, throughpassageway 46', around bottom pulley 104 and is fastened at connector106 to bag 40'. Bottom pulley 104 is fixed ,to plate 76' which, in turn,is bolted to T" 78'. The drum 102 is fitted with conventional ratchetmechanism generally indicated at 107 whereby rotation of drum 102 can becontrolled by applying forces to drum handle 108 to raise or lowerelectrode mechanism 90, and the broken line silhouette marked A in FIG.6 is intended to indicate the top or upper position of electrodeassembly 90. It is noted that the end walls 96 of assembly 90 are shapedto have approximately the same contour as top wall 22 and bottom wall24' of container l. A number of end spacers 110 are provided to keep thedistance between respective end portions 96 and top wall 22 and bottomwall 24' a suitable distance for electrochemically processing the innerfaces of end walls 22, 24. Thus, the embodiment shown in FIGS. and 7 issimilar to the embodiment illustrated in FIGS. 1-5 inasmuch as only asmall portion of the inner face of the vessel l0, is in operatingassociation with the respective electrodes 24, 26, 92, 96 at any onetime. The embodiment shown in FIG. 6, however, differs from theembodiment shown in FIGS. l5 inasmuch as the entire circumference ofelectrode assembly 90 is covered with electrode 92, and electrode 92extends in an axial direction for only a relatively small fraction ofthe axial dimension of side wall 26 of vessel 10. In the embodimentshown in FIG. 6 the electrode assembly 90 is permitted to floatupwardly, and is moved downwardly by controlling cable 100. Thus line100 is payed out to raise the electrode assembly 90, and reeled in tolower it. A suitable biased take-up reel generally indicated at 109keeps electrical lead 72 taut as electrode assembly 90 moves up and downwithin vessel 10'.

In the alternative embodiment illustrated in FIG. 8 an electrodeassembly is generally indicated at 110 and the details of itsconstruction are substantially identical to the construction describedin connection with FIGS. l-5. However, inner lateral face 94' extendssubstantially the entire length of side wall 26 and ends 96 are closelyspaced apart from the top and bottom of vessel 10 which is identical tothe vessels described in connection with the other embodiments herein.In the latter embodiment it is unnecessary to provide means for raisingand lowering or for rotating about a vertical axis since the entireinner surface of the walls of vessel 10 have an electrode mesh closelyadjacent thereto, and in operating association therewith.

Although electrode 92 is shown with an integral electrode grid aroundits entire circumference, it is contemplated that electrode grid 92 canbe assembled from a plurality of axially extending strips, each similarto electrode 34, 36, placed side by side to provide a complete 360electrode grid. In such an embodiment the respective electrode strips,e.g., 34, 36, are passed through manway 12 in a slightly foldedcondition and displacement medium container 40 is positioned within theelectrode strip circle. Thereafter the upper portions of the respectiveelectrode strips 34, 36 are fastened, as illustrated in FIG. 5 herein,to a suitable framing element, e.g., 63, with appropriate electricalconnections being made thereto. As electrolyte 125 is introduced intovessel 10, for example through valve line 80, a suitable electrolytedisplacing material is charged to container 40. If vessel 10 and itsassociated supporting structures (not shown because conventional) havebeen designed to accomodate a high density fluid, water or a relativelyhigh density displacing fluid can be added to container 10 to fill itout and provide a suitable configuration for supporting the electrodegrid, e.g., 34, 36. However, if vessel 10 and its associated supportingstructure has been designed for use solely in connection with relativelylow density fluid, it is preferred that container 40 be filled with arelatively low density material, and a particulate plastic capable ofbeing pneumatically conveyed, and capable of removal by conventionalvacuum conveyor, is preferred.

In another alternative embodiment, which is shown in FIG. 9, elongatedvertical electrode 34 is used along only one side of container 40, and acounter weight 122 is suspended from the opposite side of frame 63. Thisembodiment corresponds to that shown in FIGS. l-5, except that electrode36 is replaced by counterweight 122. In operation it is necessary torotate the electrode assembly 120, in order to electro-treat the entireinner surface of vessel 10.

In the operation of the invention, container 40 is filled with anelectrolyte displacing material, and the preferred density of thematerial utilized within bag 40 will depend, to a great extent, on theengineering details of the supporting structures of the particularvessel 10 and on the safety factor used in designing vessel 10. Forexample, in the case of a vessel which was designed, along with itssupporting structure, to contain and process a relatively low densityliquid, e.g., 0.8, it may well be advisable to avoid filling such avessel with a high density electrolyte, e.g. one having a specificgravity of 1.7. In this instance, it would be highly desirable andprobably advisable to displace most of the electrolyte with a relativelylow density displacing ma terial for reasons of safety. It iscontemplated that container 40 can be filled with a gas such as air,with a relatively low density liquid such as water, or oil, etc., orwith a solid, such as discrete particles of low density plastic whichcan be charged to container 40 and withdrawn therefrom by means ofappropriate conventional vacuum or gas stream conveying systems.

Also, it is contemplated that the displacing means used in thisinvention could also be provided in the form of a self-containedmaterial such as one or more large, preferably elongated pieces ofrelatively light weight solid material which are fastened to theelectrode assembly in place of container or bag 40. Elongated blockshaving the cross section of a truncated sector of a circle, can be used,for example, to form a cylindrical body similar to bag 40 as shown inFIG. 4. Blocks of styrofoam, or polyurethane can also be used.

It will be apparent that modifications and changes can be made withrespect to the specifically described illustrations herein withoutdeparting from the spirit or the scope of the invention. For example,although container 40 is described in connection with the illustratedpreferred embodiment has been referred to as a plastic, it iscontemplated that non-plastic, or even porous materials such as screensor mesh can be used to confine larger low density plastic spheres, forexample, providing that the material which is used for the container,and the electrolyte-displacement material are both compatible with theelectrical and chemical environment.

As indicated above, it is most preferred that the respective electrodesutilized in the invention be cooperatively associated with a relativelysmall portion of the total interior surface of the vessel 10. The mainreason for this is the fact that such an apparatus can provide therelatively high ampere per square foot surface throughput, whilerequiring a total current supply which is conveniently manageable. In apreferred method of operating, utilizing the embodiment described inFIGS. l-5 herein, it is preferred that the rotation of the electrodeassembly 32 around its vertical axis is constant, and in the samedirection. Constant rotation in the same direction better assuresuniform treatment of the vessel. However it is not essential that theelectrode assembly 32 be rotated only in a given direction, and back andforth rotation is entirely satisfactory.

With respect to the other details of operation, e.g. the current levels,etc. the operation of the present invention is governed by well knownelectrochemical processing techniques and principles.

The invention has been described in general terms, and in connectionwith several preferred embodiments. However, the specific examplesprovided herein are for illustrative purposes only, and changes can bemade without departing from the spirit or scope of the invention. Hence,the invention is not limited to the specific illustrations herein, andhas the scope of the claims appended hereto.

I claim:

I. A method of electroprocessing the electrically conductive interiorsurface of a stationary large capacity upright vessel of uniform crosssection having at least one top and one bottom opening therein whichopenings are relatively small compared to the girth of said vessel,comprising: securing anchor means in said bottom opening; attaching tosaid anchor means inflatable buoyant electrolyte displacer means havinga uniform cross-sectional shape when inflated corresponding generally tothat of the interior side wall of said vessel but having a height wheninflated that is substantially shorter than the height of said vesseland inflating said displacer means until the exterior side wall surfacethereof is adjacent to said interior side wall surface withapproximately uniform space therebetween; covering the exterior sidewall surface of said inflated electrolyte displacer means with anendless electrode, operatively connecting position control means withsaid inflated electrolyte displacer means so as to permit raising and-/or lowering thereof through at least one said top opening; introducingand maintaining an electrolyte in substantially the entire spaceseparating said exterior surface of said electrolyte displacer meansfrom said interior surface of said vessel, the actual amount ofelectrolyte in said vessel being substantially less than the capacitythereof, and the combined volumes of said electrolyte and said submergedelectrolyte displacer means being substantially equal to said vesselcapacity; passing an electrical current through said electrolyte betweensaid electrode and said interior surface; and, raising and/or loweringsaid inflated electrolyte displacer means to electroprocess all of saidinterior side wall surface.

2. The method called for in claim 1 wherein the shape of the exteriorbottom surface of said electrolyte displacer means when inflated issubstantially the same as that of the inner surface of the bottom ofsaid vessel, covering said bottom surface of said inflated displacermeans with an electrode, and passing an electrical current through saidelectrolyte between said bottom electrode and said inner bottom surfaceof said vessel when said inflated electrolyte displacer means is in itslowermost operating position so as to also electroprocess said innerbottom surface.

3. The method called for in claim 2 wherein the shape of the exteriortop surface of said electrolyte displacer means when inflated issubstantially the same as that of the inner surface of the top of saidvessel, covering said top surface of said inflated displacer means withan electrode, and passing an electrical current through said electrolytebetween said top electrode and said inner top surface of said vesselwhen said inflated electrolyte displacer means is in its uppermostoperating position so as to also electroprocess said inner top surface.

1. A METHOD OF ELECTROPROCESSING THE ELECTRICALLY CONDUCTIVE INTERIORSURFACE OF A STATIONARY LARGE CAPACITY UPRIGHT VESSEL OF UNIFORMCROSS-SECTION HAVING AT LEAST ONE TOP AND ONE BOTTOM OPENING THEREINWHICH OPENING S ARE RELATIVELY SMALL COMPARED TO THE GIRTH OF SAIDVESSEL, COMPRISING: SECURED ANCHOR MEANS IN SAID BOTTOM OPENING;ATTACHING TO SAID ANCHOR MEANS INFLATABLE BUOYANT ELECTROLYTE DISPLACERMEANS HAVING A UNIFORM CROSS-SECTIONAL SHAPE WHEN INFLATED CORRESPONDINGGENERALLY TO THAT OF THE INTERIOR SIDE WALL OF SAID VESSEL BUT HAVING AHEIGHT WHEN INFLATED THAT IS SUBSTANTIALLY SHORTER THAN THE HEIGHT OFSAID VESSEL AND INFLATING SAID DISSHPLACER MEANS UNTIL THE EXTERIOR SIDEWALL SURFACE THEREOF IS ADJACENT TO SAID INTERIOR SIDE WALL SURFACE WITHAPPROXIMATELY UNIFORM SPACE THEREBETWEEN; COVERING THE EXTERIOR SIDEWALL SURFACE OF SAID INFLATED ELECTROLYTE DISPLACER MEANS WITH ANENDLESS ELECTRODE, OPERATIVELY CONNECTING POSITION CONTROL MEANS WITHSAID INFLATED ELECTROLYTE DISPLACER MEANS SO AS TO PERMIT RAISING AND/ORLOWERING THEREOF THROUGH AT LEAST ONE SAID TOP OPENING; INTRODUCING ANDMAINTAINING AN ELECTROLYTE IN SUBSTANTIALLY THE ENTIRE SPACE SEPARATINGSAID EXTERIOR SURFACE OF SAID ELECTROLYTE DISPLACER MEANS FROM SAIDINTERIOR SURFACE OF SAID VESSEL, THE ACTUAL AMOUNT OF ELECTROLYTE INSAID VESSEL BEING SUBSTANTIALLY LESS THAN THE CAPACITY THEREOF, AND THECOMBINED VOLUMES OF SAID ELECTROLYTE AND SAID SUBMERGED ELECTROLYTEDISPLACER MEANS BEING SUBSTANTIALLY EQUAL TO SAID VESSEL CAPACITY;PASSING AN ELECTRICAL CURRENT THROUGH SAID ELECTROLYTE BETWEEN SAIDELECTRODE AND SAID INTERIOR SURFACE; AND, RAISING AND/OR LOWERING SAIDINFLATED ELECTROLYTE DISPLACER MEANS TO ELECTROPROCESS ALL OF SAIDINTERIOR SIDE WALL SURFACE.
 2. The method called for in claim 1 whereinthe shape of the exterior bottom surface of said electrolyte displacermeans when inflated is substantially the same as that of the innersurface of the bottom of said vessel, covering said bottom surface ofsaid inflated displacer means with an electrode, and passing anelectrical current through said electrolyte between said bottomelectrode and said inner bottom surface of said vessel when saidinflated electrolyte displacer means is in its lowermost operatingposition so as to also electroprocess said inner bottom surface.
 3. Themethod called for in claim 2 wherein the shape of the exterior topsurface of said electrolyte displacer means when inflated issubstantially the same as that of the inner surface of the top of saidvessel, covering said top surface of said inflated displacer means withan electrode, and passing an electrical current through said electrolytebetween said top electrode and said inner top surface of said vesselwhen said inflated electrolyte displacer means is in its uppermostoperating position so as to also electroprocess said inner top surface.